console.log(11/5);
console.log(Math.ceil(11 / 5));

var arr = [1,2,3];
let result = arr.map(obj => obj*obj);
console.log(result);

var arr = [{"id":1,"name":"tom1"},{"id":3,"name":"tom2"},{"id":5,"name":"tom3"}]
var res = arr.map(obj => obj.id);
console.log(res);